Transmission ratio brake assemblies include a plurality of friction discs in a brake pack. The discs are alternately splined at the outside diameter and inside diameter, respectively. Generally, the outside diameter spline discs are in toothed engagement with a spline formed in a transmission housing while the inside diameters spline discs are in toothed engagement with a rotatable transmission component, such as a hub or a gear.
A fluid operated piston, slidably disposed in the housing is pressurized to frictionally engage the discs. A backing plate is also splined with the housing and restrained in one axial direction by a retaining ring.
The backing plate and retaining ring provide reaction members to limit axial movement in one direction of the brake back during brake engagement. The reaction force imposed on the backing plate and retaining ring is transmitted to the housing through a groove wall in which the ring is disposed.
In most transmissions, at least one brake assembly is located at one end of the housing, such that visual inspection of the retaining ring placement is difficult. If the ring is not properly seated, it will generally disengage in the groove leaving the brake inoperable at final test on the assembly line. This gives rise to time consuming repair since the transmission must be disassembled, repaired and reassembled.